Preheat the oven to 350 degrees F. Lightly oil and flour 9x13 inch pan.
In a large bowl, sift together flour, sugar, baking soda, salt, and cocoa powder.
In another large bowl, whisk together oil, buttermilk, eggs, food coloring, vinegar, and vanilla.
Combine the dry ingredients into the wet ingredients in a stand mixer until just combined.
Bake until the cake pulls away from the side of the pans slightly, and a toothpick inserted in the center of the cakes comes out clean, about 30 minutes.
Allow cake to cool before frosting or cubing for parfait.
Whisk milk and pudding about 2 minutes. Fold in cool whip. Refrigerate until ready to make parfaits.
Layer cake cubes in the bottom of clear glasses or a large bowl.
Spoon pudding over cake. Repeat with another layer of cake and another layer of pudding.
Top with whipped cream or cool whip.
Store in refrigerater.